Streptomycetes are Gram-positive bacteria of Actinomycetales. These organisms can produce many economically important secondary metabolites. With the development of molecular biology, gene sequencing technology and synthetic biology, people gained a better understanding of the Streptomyces family. The means to transform genome on the molecular level is also increasing. By simplifying the Streptomyces genome rationally and efficiently, it will improve the yield and quality of the metabolites as well as reduce the consumption of the substrates. Markerless knockout is an important way to carry out genetic modification. Here we describe novel genome modification techniques developed for Streptomyces in recent years with focus on the markerless knockout technologies.
Chromosomes, Bacterial ; genetics ; Gene Knockout Techniques ; methods ; Genes, Bacterial ; genetics ; Streptomyces ; genetics

Objectives To examine the clinical usefulness of magnetic resonance spectroscopy (MRS) on assessment of vascular dementia (VD) in patients with stroke; the relationships between metabolic changes of brain and clinical symptom improvements after giving rivastigmine in these patients.Methods 20 stroke patients without VD, male 17, female 3, with a mean age of (71.7?4.7) years old; 23 stroke patients with VD, male 20, female 3, a mean age of (72.9?5.1) years old; 20 normal volunteers were studied, a mean age of (70.9?4.8) years old. MRS was performed in all these patients. The patients with VD were prescribed rivastigmine hydrogen tartrate ("Exelon", Norvatis), and given MRS assessment half a year later.Results The patients with VD had a significantly lower N-acetyl aspartate/Creatine (NAA/Cr) ratio (mean?SD: left: 0.57?0.30; right: 0.66?0.29) and higher Choline/Creatine (Cho/Cr) ratio (mean?SD: left: 1.79?0.52; right: 1.97?0.44) in bilateral temporal hippocampus area, compared to those without VD (mean?SD: NAA/Cr: left, 0.91?0.31; right, 0.87?0.27, P

Objective:To study the healing effect of Chitin dressing on second-degree scalds in mice and rabbits respectively.Methods:The model of the second-degree scald was established in mice and rabbits respectively by vapour and hot water;the healing time was observed and the tissue specimens were obtained from the scalds for pathologic analysis.Results:Compared with the contrast group,the healing time in chitin dressing treated group was shorter(P

Aim To investigate TY501′s role in bleo-mycin ( BLM )-induced pulmonary fibrosis in rats. Methods Forty rats were randomly divided into 5 groups, including the sham operation, BLM, PFD, TY501(high and low dose) groups. After administra-tion of BLM intratracheally, PFD and TY501 were giv-en in each group daily, according to the dosage de-signed during 21 days. Lung coefficient, PaO2 were tested before killing the rats. The contents of ALB, ALP, LDH, GSH, HYP were detected by regent kit respectively. PCⅢ and COL4 were determined by ELISA. Results ( 1 ) Some indicators of alveolitis in early stage of IPF: the contents of lung coefficient in three treatment groups were lower and PaO2 was higher than those in BLM group ( P<0. 05 ); compared with BLM group, the contents of ALB, ALP, LDH in the treatment groups reduced on 21 st day ( P<0. 05 );the expression of GSH in BLM group was increased for feedback regulation and higher than the treatment groups and the sham operation group (P<0. 05);(2) some indicators of pulmonary interstitial fibrosis in late stage of IPF:the expressions of HYP, PCⅢand COL4 were reduced after the treatment. There were signifi-cant differences compared with BLM group ( P <0. 05 ) . Conclusions TY501 is valuable for the ther-apy of IPF, the same as the positive drug pirfenidone. TY501 attenuates BLM-induced pulmonary fibrosis, which may be related to the affection of TGF-βpathway and inhibition of MMPs.

Objective To investigate the influencing factors of preterm premature rupture of membranes and maternal outcomes. Methods 326 cases with PPRM singleton were selected as the study group in our hospital,and 300 singleton cases with preterm premature rupture of membranes as the control group. Retrospective investigation of the pregnant women and neonatal was performed. Results By single factor analysis,there was no significant difference between the two groups of gestational hypertension,gestational diabetes,uterine dysplasia, uterine scar incidence(P > 0.05);The incidence of reproductive tract infection and fetal abnormalities in study group was higher than that in the control group(P<0.05). The single factor analysis in multivariate logistic regres-sion with statistical difference analysis of reproductive tract infection and abnormal fetal position for preterm prema-ture rupture of the placenta affect independent risk factors. The incidence of neonatal asphyxia and neonatal pneu-monia in the study group was higher than that in control group,and the neonatal weight was lower than the control group,Apgar score was lower than that in the control group(P<0.05). Conclusion the reproductive tract infec-tion and abnormal fetal position of preterm premature rupture of the placenta membranes affect the independent risk factors for preterm premature rupture of membranes ,adverse neonatal outcomes,neonatal asphyxia and the incidence of pneumonia,and light weight need further research.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of national bloodstream infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:During the study period，9 035 strains of Gram-negative bacteria were collected from 51 hospitals，of which 7 895（87.4%）were Enterobacteriaceae and 1 140（12.6%）were non-fermenting bacteria. The top 5 bacterial species were Escherichia coli（ n=4 510，49.9%）， Klebsiella pneumoniae（ n=2 340，25.9%）， Pseudomonas aeruginosa（ n=534，5.9%）， Acinetobacter baumannii complex（ n=405，4.5%）and Enterobacter cloacae（ n=327，3.6%）. The ESBLs-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus spp. were 47.1%（2 095/4 452），21.0%（427/2 033）and 41.1%（58/141），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（58/4 510）and 13.1%（307/2 340）；62.1%（36/58）and 9.8%（30/307）of CREC and CRKP were resistant to ceftazidime/avibactam combination，respectively. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 59.5%（241/405），while less than 5% of Acinetobacter baumannii complex was resistant to tigecycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 18.4%（98/534）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of main Gram-negative bacteria resistance among different regions，with statistically significant differences in the prevalence of CRKP and CRPA（ χ2=20.489 and 20.252， P<0.001）. The prevalence of CREC，CRKP，CRPA，CRAB，ESBLs-producing Escherichia coli and Klebsiella pneumoniae were higher in provinicial hospitals than those in municipal hospitals（ χ2=11.953，81.183，10.404，5.915，12.415 and 6.459， P<0.01 or <0.05），while the prevalence of CRPA was higher in economically developed regions（per capita GDP ≥ 92 059 Yuan）than that in economically less-developed regions（per capita GDP <92 059 Yuan）（ χ2=6.240， P=0.012）. Conclusions:The proportion of Gram-negative bacteria in bloodstream infections shows an increasing trend，and Escherichia coli is ranked in the top，while the trend of CRKP decreases continuously with time. Decreasing trends are noted in ESBLs-producing Escherichia coli and Klebsiella pneumoniae. Low prevalence of carbapenem resistance in Escherichia coli and high prevalence in CRAB complex have been observed. The composition ratio and antibacterial spectrum of bloodstream infections in different regions of China are slightly different，and the proportion of main drug resistant bacteria in provincial hospitals is higher than those in municipal hospitals.

ObjectiveTo determine the therapeutic effect of Gegentang granules on a disease-syndrome mouse model combining human coronavirus 229E （hCoV-229E） pneumonia with Hanshi Yidu Xifei syndrome in vivo. MethodMice were randomly divided into normal group， infection group， cold-dampness group， model group， chloroquine phosphate group （0.18 g·kg^-1）， interferon-α2b （IFN-α2b） group （1.83×10⁶ U·kg^-1）， Gegentang granules high-dose and low-dose groups （6.6， 3.3 g·kg^-1） with 10 mice in each group. Cold-dampness environment and hCoV-229E infection were used for modeling， and the general status and lung index of mice in each group were observed. The viral load in lung tissue was detected by real-time fluorescent quantitative polymerase chain reaction （Real-time PCR）， the pathological changes in lung tissue were evaluated by hematoxylin-eosin （HE） staining， the levels of serum gastrointestinal hormones and inflammatory factors in lung tissue were detected by enzyme-linked immunosorbent assay （ELISA）， and the percentage of peripheral blood lymphocytes was detected by flow cytometry. ResultComparing with model group， Gegentang granules could significantly alleviate the physical signs of Hanshi Yidu Xifei syndrome， including listlessness， weakness of limbs， sticky stool， etc. Comparing with model group， Gegentang granules high-dose group significantly reduced lung index， histopathological score of interstitial lung and bronchus， and the level of serum motilin （P<0.05， P<0.01）， two doses of Gegentang granules could significantly increase the level of serum gastrin （P<0.05， P<0.01）， the percentage of CD4⁺， CD8⁺ T lymphocytes in peripheral blood （P<0.05， P<0.01）， and the level of tumor necrosis factor-α （TNF-α） in lung tissue was significantly decreased （P<0.01）， and the level of interleukin-6 （IL-6） showed decreasing tendency. ConclusionGegentang granules has therapeutic effect on model mice. It can improve the appearance and behavior characterization， regulate the level of gastrointestinal hormones， decrease lung index and histopathological score， and possibly play an immunomodulatory role by inhibiting the expression of inflammatory cytokines in lung tissue and restoring the percentage of peripheral blood lymphocytes.

ObjectiveThe human angiotensin converting enzyme2 （hACE2） transgenic mouse model was used to clarify the antiviral efficacy of BD-77 against a novel coronavirus SARS-CoV-2 and explore the action mechanism of BD-77 against SARS-CoV-2. MethodSARS-CoV-2 Omicron and Delta variant strains-infected VeroE6 cell models were established and administered with BD-77 to observe the antiviral effect of BD-77 in vitro. A kit was used to detect the effect of BD-77 in vitro on the binding of spike S protein of SARS-CoV-2 virus （Delta/Omicron） to angiotensin converting enzyme2 （ACE2）. Chromatography was adopted to detect the binding of BD-77 to the S protein and N protein of the novel coronavirus. hACE2 transgenic C57BL/6 mice were divided into a blank control group， SARS-CoV-2 infection group， BD-77 administration groups of 37.5 mg·kg^-1 and 75 mg·kg^-1， with eight mice in each group. The pneumonia model of SARS-CoV-2-infected hACE2 transgenic mice was built to observe the survival of the mice， detect the virus titer of the lung tissue of the mice， and observe the lesions in the lung tissue. ResultBD-77 had a certain inhibitory effect on Omicron and Delta variant strains in vitro， with median inhibitory concentration （IC₅₀） of 526.3 mg·L^-1 and 653.0 mg·L^-1， respectively. BD-77 had no significant inhibitory effect on the binding of the S protein of WT， Omicron， and Delta variant strains of SARS-CoV-2 to ACE2 and had no binding effect with the S protein and N protein of the novel coronavirus. No mice in the blank group died， while the mortality rate of SARS-CoV-2-infected mice was 75%. There was a large amount of virus replication in the lung tissue of the mice and large areas of inflammatory infiltration in the lung tissue and interstitium. Compared with the model group， BD-77 administration groups of 37.5 mg·kg^-1 and 75 mg·kg^-1 could reduce the mortality of mice， significantly lower the virus titer in the lung tissue of mice （P<0.05）， and improve lung lesions. ConclusionBD-77 demonstrated significant inhibitory effects against SARS-CoV-2 virus in vitro and in vivo. However， its mechanism of action did not involve direct inhibition of the virus itself or intervention in the virus-host binding process. This finding suggests that the mechanism of action of BD-77 needs to be thoroughly investigated and elucidated by further experiments.

ObjectiveTo observe the therapeutic effect of BD-77 by nebulized inhalation on animal models of various respiratory viral infections and investigate the mechanism of broad-spectrum antiviral action of BD-77 using proteomics. MethodThe influenza virus H1N1/FM1 experiment used ICR mice and divided them into a normal group， model group， Tamiflu group， and BD-77 groups of 75 and 37.5 g·L^-1 for inhalation of 20 min and 25 min. Human coronavirus 229E and OC43 experiment divided the BALB/c mice into a normal group， model group， chloroquine phosphate group， and BD-77 groups of 75， 37.5， 18.75， and 9.375 g·L^-1， with 10 mice in each group. Influenza virus H1N1/FM1 and human coronaviruses 229E and OC43 infection-induced pneumonia models were used to detect mouse lung index， and real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） was used to detect the viral load in lung tissue. Enzyme-linked immunosorbent assay （ELISA） was used to detect related inflammatory factors in lung tissue， and proteomics analysis was performed on the lung tissue of OC43-infected mice. ResultCompared with that in the normal group， the lung index of mice in each infection group was significantly increased （P<0.01）， and viral nucleic acid could be detected in the lung tissue of mice infected with human coronaviruses 229E and OC43. The levels of interleukin-6 （IL-6）， IL-10， and tumor necrosis factor-α （TNF-α） in the lung tissue of mice infected with human coronavirus 229E were all significantly increased （P<0.01）. BD-77 could significantly reduce the lung index of mice infected with influenza virus H1N1/FM1 and human coronaviruses 229E and OC43 （P<0.05， P<0.01）， cut down the viral load in the lungs of mice infected with human coronaviruses 229E and OC43 （P<0.01）， and lower the contents of IL-6， IL-10， and TNF-α in the lung tissue of mice infected with human coronavirus 229E （P<0.01）. Proteomics analysis of the lung tissue of OC43-infected mice showed that BD-77 regulated the AMPK signaling pathway， TNF signaling pathway， NOD-like signaling pathway， IL-17 signaling pathway， Forkhead box protein O （FoxO） signaling pathway， transforming growth factor-β （TGF-β） signaling pathway， and other signaling pathways. ConclusionNebulized inhalation of BD-77 is effective in treating pneumonia caused by influenza virus H1N1/FM1 and human coronaviruses 229E and OC43 infection in mice and may exert its antiviral effects by regulating the balance of cellular metabolism， enhancing the immune function of the host， and attenuating inflammatory responses.

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor in adults and is poorly controlled. Previous studies have shown that both macrophages and angiogenesis play significant roles in GBM progression, and co-targeting of CSF1R and VEGFR is likely to be an effective strategy for GBM treatment. Therefore, this study developed a novel and selective inhibitor of CSF1R and VEGFR, SYHA1813, possessing potent antitumor activity against GBM. SYHA1813 inhibited VEGFR and CSF1R kinase activities with high potency and selectivity and thus blocked the cell viability of HUVECs and macrophages and exhibited anti-angiogenetic effects both in vitro and in vivo. SYHA1813 also displayed potent in vivo antitumor activity against GBM in immune-competent and immune-deficient mouse models, including temozolomide (TMZ) insensitive tumors. Notably, SYHA1813 could penetrate the blood-brain barrier (BBB) and prolong the survival time of mice bearing intracranial GBM xenografts. Moreover, SYHA1813 treatment resulted in a synergistic antitumor efficacy in combination with the PD-1 antibody. As a clinical proof of concept, SYHA1813 achieved confirmed responses in patients with recurrent GBM in an ongoing first-in-human phase I trial. The data of this study support the rationale for an ongoing phase I clinical study (ChiCTR2100045380).